We don't know enough to do any of those yet. These are ideas that have not been tested at all, naturally, as we don't have any spare planets to test them on.
And Mars is very different from Earth. Put Earth in Mars orbit for instance, and it's oceans would freeze over. Mars itself probably represents the end point of a planet like Earth, but smaller, with no continental drift and no ionosphere, left to evolve for billions of years.
And we don't know how to terraform the Earth - at least not quickly. It took millions of years in the past. And how do we know that this is the only endpoint? And Earth itself went through snowball phases for millions of years.
But - the main thing is - that the projects are irreversible. Especially if you add life to Mars, no way to remove it again. Also releasing its dry ice reserves, and melting its water - no way to turn that back.
For instance, one possibility - Mars has at least enough water to cover its surface to a depth of 12 meters. But it also has equatorial dry deserts that are dry, we believe, for kilometers into the surface.
The way they dried out is that they had ice long ago - when Mars was tilted so far it had equatorial ice sheets. But because of the near vacuum of the atmosphere - even though well below the sublimation point of the ice - still - the ice evaporates far more quickly than it normally would. So surface layers of ice evaporate into the atmosphere. Then lower layers evaporate and migrate upwards to take their place - and over millions of years - that dried out the equatorial regions, we believe, for kms below the surface.
So melt that water, thicken up the atmosphere - and one possible outcome might be that all the water just gets absorbed into the dry equatorial regions of Mars. Leaving nothing left.
But there are many other things to go wrong also. Basically it is a huge experiment, with no clear idea of what would happen - especially - how the lifeforms would evolve after they are introduced to Mars, or what they would do to the planet or the climate.
The physics alone is tricky, when you have limited knowledge still of Mars below the surface. But when you add to that, the possibility of life evolving in a myriad different ways - and transforming the atmosphere - either working with you or against you or sending it in a totally unexpected direction - and then add in the need to set up some biological feedback cycles to keep everything in balance.
And - is clear we don't have the knowledge to do it.
But as well as that - it's a thousand year project on the most optmistic projections. Some say - right so we'd better start right now given that it will take so long. But - how can we know enough to say how best to terraform the planet? How do we even know that our descendants 30 generations from now will want the same things we want? Even today there is a lot of diversity of opinion about what's the best thing to do.
And - more than all that - how are we going to keep it up for 1000 years. Will any country or administration commit to a 1000 year project? Or the world as a whole? I don't think so.
Especially one of the motivations is because people are scared that we might lose our technology. But it's the other way around, this is a project a civilization should only start on if it is so confident that it predicts that it is still a highly technological society a thousand years from now.
And if you worry that Earth will lose its technology - how is Mars going to survive if that happens? How likely is it that Mars would somehow retain high technology and be able to build spaceships and space mirrors etc, when Earth has lost that technology?
So - I think the time for a project like this is a few centuries from now. Maybe 500 years from now. And maybe we will know enough then and have such awesome technology that we can complete it even in a century. Maybe we will contact ETs who have terraformed planets and can advise us about what can go right and what can go wrong. Or see the remnants of their attempts on nearby solar systems?
Or find out more about exoplanets and learn things that way?
Also - if you want to experiment - well rather than experiment with Mars, build a Stanford Torus. Okay that's a big expensive project, perhaps tens of billions of dollars, maybe even more. But it's far far less expensive than terraforming Mars. And you can complete it in maybe 40 years, not 1000 years. And there are enough materials just in the asteroid belt to build Stanford Torus habitats with surface area of a thousand times the surface area of Mars.
Want to experiment? You can have ten different versions of Mars, or a hundred different versions, in your habitats and try out what happens to each one. If we get to the level of technology where terraforming is easy - then it will also be easy to build Stanford Torus habitats - and is not at all clear that we will need other planetary surfaces at that point.
So - I say - wait at least a century, probably five centuries, and re-evaluate. That is unless there is some extraordinary development - e.g. very rapid evolution of methods of simulating entire planets in a computer to a high level of accuracy - including evolution of lifeforms on those planets - or study of exoplanets - or Stanford Torus type settlements results or whatever. But - really excellent conclusive data, not just ideas and hunches and interpolations.
See also Imagined Colours Of Future Mars - What Happens If We Treat A Planet As A Giant Petri Dish?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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